Step 1. Find out what you’ve got:
So let's look at the green assessment process.
The best way I know of starting this is to have a look at what’s going on under the turf and you can get a good idea of this by taking a deep profile sample that will show you a cross section through the green. The best method is to use a sampler like the one below:
You are looking to establish the depth of the thatch layer, any distinct layers in the profile, any funny smells from it and how moist or dry it is. If you can get a deep sample (deeper than 150mm/6″) you should be able to see the contrast between the natural soil the green was built with and the “improved horizon” (top 100mm/4″) where all of the top-dressing has been going over the years. You should also be able to detect any hard, compacted pans as you try to get the sampler in. Make a note of the depth of any noticeable hard layers.
Take several samples across the green and note down what you see with reference to the above points. If you can take a sample across the boundary of a normal area/brown area you might be able to see a marked difference in the conditions below the turf. A sample taken from an LDP affected area will typically fall apart as the soil will be powdery dry.
The soil profile sample.
First of all, assuming that you managed to get at least one nice slice out of your green using a sampler (these are about £100 new and a good investment), or a border spade as a reasonable alternative. If the cost of a proper sampler is off putting, try speaking nicely to your local golf club greenkeeper, who might have an old hole cutter lying around un-used. This will give you a cylindrical profile sample that you can split down the middle with a knife. You should take a sample from any area that looks distinctly different and at least one from an area you would consider to be in good condition.
Soil Texture and Layers
Have a look at the soil profile to see if there are any distinct layers. The soil should ideally look like one homogenous mass without distinct layers of different materials. In most cases on bowling greens if you take a deep enough sample, you will see at least one distinct horizon (layer) change where the top 100-150mm is distinctly different in texture from the soil below. This marks what I’ve termed the improved horizon, which identifies the depth to which most of the regular maintenance has taken effect, especially aeration and top-dressing. This means that most greens will show a markedly sandier improved horizon than the soil below that level.
Root Density and Depth
You should be able to see (you might have to break the sample apart) evidence of root growth down through the profile. Root depth can be variable and although healthy turf will tend to have deeper roots, don’t worry if yours don’t go all the way to the bottom of the sample. You might see large masses of roots going down old core holes in your samples, proving that if we make it easier (by aerating to overcome compaction) for roots to get down, they will. Deeper roots make for a more resilient turf due to the plants’ ability to obtain moisture from deeper in the soil. However, root depth is directly correlated with leaf tissue mass, so it’s common for roots to recede upwards as the grass is mown shorter.
Root mass is important too. The soil should be held together with a great mass of tiny grass roots and if you break the sample apart you should see a high percentage of fresh, white roots which indicates that the plants are growing vigorously and producing new root growth.
The first thing you will notice is thatch, which is the dense mat at the top of the sample directly under the grass or at least the bit where the grass should be!
Thatch is made up of dead and dying grass roots, shoots and leaf tissue. Some thatch is essential to allow the turf to stay knitted together in a cohesive unit, but too much is bad news. The optimum level of thatch is around 5-10mm and you should be concerned about it if is significantly more than this.
A thick thatch layer shows that the natural processes that recycle organic material into humus and soil nutrients aren’t working at capacity. On bowling greens this is commonly due to a lack of microlife in the soil.
The thatch layer might be dense, wet and smelly and if it is, you can probably squeeze excess moisture out of it. In this case the green will be slow and unpredictable and susceptible to disease outbreaks. In dry weather the same thatch layer can become hard and dry and impermeable to water, causing the green to be bumpy and difficult to keep grass cover.
Related to everything we’ve discussed so far is a condition known as Rootbreak. Root break is identified by the sample falling apart at a particular horizon in the profile. This can happen due to compaction or layering of different materials in the soil. Essentially it means that the roots have either stopped at a layer and have gone no deeper due to it being repellent (anaerobic or dry) or hard and impermeable. In a lot of cases where the thatch layer is thick, dense, wet and anaerobic a rootbreak will appear directly at the bottom of the thatch layer, meaning that all of the roots are existing within the thatch.
Rootbreak is common on greens that have been subjected to a variety of top-dressing materials over the years, or that have deep seated compaction leading to anaerobic (black) layers or that have built up a dense and anaerobic thatch layer.
Localised Dry Patch
LDP causes large areas and even whole greens to resist moisture. The soil has become Hydrophobic. Water will lie on the green surface for a long time and the soil underneath will remain powder dry and unable to support plant life. The result is large brown patches on the surface where the thatch eventually dries out so much that it becomes hard and brittle. At this point it will shrink to below surface level, causing large pans of low lying turf which of course affect the performance of the green to a level that is unacceptable. Temporary measures such as sarrel rolling and wetting agent application can help to get water into the green, but the water still wont adhere to the soil particles below making sure that most of the irrigation water runs straight through to the drains.
Chemical and Textural Analysis
At this stage in the process it will be very helpful to have a soil chemical analysis carried out. It also makes sense to collect the required samples for this as you go. In many cases a soil analysis can help to identify the green’s tendency towards certain problems. The Base Saturation of your soil dictates the pH and Cation Exchange Capacity and these are critically important to the overall availability of nutrients in the soil.
Other common chemical imbalances include high Iron deposits due to repeated use of Sulphate of Iron based fertilisers and mosskillers and poor aeration practices. High salt content is also common due to long term use of mineral fertilisers.
A thorough Chemical Analysis, properly interpreted and used to inform your on-going maintenance is highly valuable.
Textural analysis will tell you where your green's soil is on the Soil Texture Triangle and this can be invaluable for making decisions on top-dressing and in communicating these decisions to your members.
What Chemical and Textural Analysis includes
My Chemical and Textural Analysis service will detail the following information about your green:
Chemical Analysis: A comprehensive set of tests leading to analysis of all Primary, Secondary and Trace elements, Cation Exchange Capacity, Base Saturation, Electrical Conductivity, Organic Matter and pH
Textural Analysis: Your rootzone's (top-soil) condition in terms of soil texture and where it registers on the Soil Texture Triangle, determined by laser diffraction. Soil texture dictates drainage, moisture retention and soil nutrient availability.
Report and Recommendations
All testing is carried out independently by one of the UK's top soil laboratories and fully interpreted and reported back to you by me. I will provide you with a comprehensive report and recommendations for maintenance based on the results.
Drop me a line if you're not sure which analysis to go for.